Electric feathering control



Nov. 9, 1943. v y M. c. BEEBE, JR 2,333,973

ELECTRIC FEATHERING CONTROL Filed Nov. 16, 1939 2 Sheets-Sheet 1 INVENTOR ATTORNEY M. c. BEEBE, JR 2,333,973

ELECTRIC FEATHERING CONTROL Nov. 9, I943.v

2 Sheets-Sheet 2 Filed NOV. 16, 1939 INVENTOR ATTORNEY lable-pitch propeller, and

Patented Nov. 9, 1943 UNITED STATES PATENT OFFICE ELECTRIC CONTROL I Murray 0. Beebe, Jr., Glastonbury, Com, as-

signor to United Aircraft Corporation, East Hartford, Conn, a corporation of Delaware Application November 16, 1939, Serial No. 304,780

11 Claims. (01. 170-163) This invention relates to improvements in controls for controllable-pitch propellers and has particular reference to an improved control for a feathering type controllable-pitch propeller.

An object of the invention resides in the provision of an improved control for the pitch changing mechanism of a feathering type propeller effective to discontinue operation of the pitch changing mechanism when the propeller has reached a feathered condition but which may be manually actuated to continue operation of the pitch changing mechanism after the feathered condition has been reached to return the propeller blade from the feathered condition to the operative range of propeller pitch angles.

A further object resides in the provision of a propeller feathering and unfeathering pump control of the character indicated which may operate to discontinue operation of a propeller feathering pump .when the feathered condition of the propeller has been reached and also when the propeller has been returned from its feathered condition to its operative range of pitch angles.

further modified form of feathering and unfeathering control for a feathering type controllable-pitch propeller.

Referring to the drawings in detail, and particularly to Fig. 2, the numeral it generally indicates a propeller driving engine from which projects a propeller drive shaft [2 carrying a controllable-pitch. propeller, generally indicated at H. The engine has been indicated by a fragject matter of the invention. For a more detailed description of a suitable type of propeller refer- Other objects and advantages will be more particularly pointed out hereinafter or will become apparent as the description proceeds.

In the accompanying drawings, in which like reference numerals are used to designatesimilar matically illustrated in three slightly different forms a suitable embodiment for the purpose of disclosing the invention. The drawings, however,

, are for the purpose of illustration only and are 7 parts throughout, there is somewhat diagramnot to be taken as limiting the scope of the invention as it will be apparent to those skilled in the art that various changes may be made in the illustrated arrangements without in any way exceeding the scope of the invention.

In the drawings, Fig. l is a somewhat diagrammatic illustration of one form of control for a controllable-pitch .distllbuting'valve of the propeller shown in Fig. 2

and shows the valve in a different operative position from theposition illustrated in Fig. 2.

Fig. 4 is a diagrammatic illustration of a somewhat modified form of a feathering and unfeathering control for a feathering type control- Fig. 5 is a diagrammatic ence may be had to United States Patent No. 2,280,714, granted April 21, 1942, by Erle Martin for Feathering propeller control, and assigned to the assignee of this application.

In general, such a propeller may have a .plurality of movably mounted blades, one of which is indicated at 18, supported in a hub structure l8 mounted on the driveshaft l2. The blades are operatively connected by suitable means, such as the gear elements 20 and 22, with a hydraulic blade turning mechanism generally indicated at 24 and including a fixed cam 26, a movable cam 28 carrying-the gear 22, and a piston 30 reciprocable in a domed cylinder 32 and carrying cam followers, as indicated at 84, to rotate the rotatable cam 28 relative to the fixed cam 26 upon reciprocation of the piston in the cylinder 32. The piston acts under the influence of a preponderance of hydraulic forces or of hydraulic and centrifugal forces acting on one side or the other t's' fiieof to move the cam followers 34 through the cam slots, as indicated at 36 and 38, to rotate the movable cam member 28 and thereby rotate the propeller blade-I6 in a pitch changing direction by reason of the inter-engagement of the gear elements 20 and 22.

The propeller has a constant speed range of pitch angles in which it is under the control of the speed responsive governor 40, and also has a feathered position in which the blades are turned to a position substantially parallel to the axis of the shaft l2, to which position the blades are brought by the action of the motor driven featherillustration of a still ing pump 42. The pump 42 is'also operative to return the propeller from the feathered position to the governor controlled range of pitch angles in a manner which will presently appear. 7

lubricating oil pump 44 tothe governor 40 where its pressure may, if desired, be increased by. a booster pump 40 in a manner well known to the art and particularly'illustrated and described in United States Patent No. 2,204,640, issued 18, 1940, to Elmer E. Woodward;

From the governor intake or from the outlet June of the booster pump 48, the oil is supplied to a.

ernor drive shaft 88, asis particularly shown in the United States Patent 2,204,640 referred'to above, so that the governor actuated valve is operative to connect the interior of the drive shaft I2 ahead of the plug 82 with hydraulic fluid under a pressure regulated by the governor or booster pump relief valve 58, or with drain through the shaft 88, depending upon the engine speed change demands of the speed responsive governor 40. This action of the governor valve operates to connect the space to the left of the piston .00, as viewed in Fig. 2, with pressure or with drain through the conduit 80, the valve 84, the interior of the shaft II, the plug 82, the collector ring 80 and the conduit 48. When subjected to fluid pressures not greater than the pressure of'the output of the booster pump 48, the distributing.

through the conduit 88 extending concentrically through the shaft I2 and plug 82, the passages I and I2 and the annular groove 14 in the slidable valve stem 08. Since the lubricating oil pump 44 operates whenever the engine is operating there will always be fluid pressure acting upon the outer or pitch reducing side of the piston 30 whenever the engine and propeller are operating under, power. As the governor oil pressure as maintained by the relief valve 58 is higher than pressure of the engine lubricating oil as maintained by the pressure relief valve 18, when the governor actuated valve is operated to connect the space at the inner side of the piston 00 with the booster pump 48 the greater pressure produced by this pump acting on the pitch increasing side of the piston 80 will move the piston to increase the pitch of the propeller. -When the governor actuated valve is positioned to connect the space at the inner or pitch increasing side of the piston 80 .with drain, however, the pressure of the engine lubricating oil on the outer or pitch decreasing side of the piston will assist the action of centrifugal force acting on the propeller blades to move the piston in a pitch decreasing direction to turn the blades to a lower pitch.

position, all as particularly set forth in United with the channel 48 and simultaneously block] the channel I00 from the channels 80 and so assaovs I v States Patent No. 2,280,714, referred to above.

- referred to above.

The spring I44 of the distributor valve 04 exerts a force on the plunger 88 of the distributor valve such that the plunger does not materially I change its position during governor controlled operation or during the feathering operation of the propeller, but moves to change the fluid connection to the pitch changing motor for unfeathering operation of the motor, the position of this valve for the unfeathering operation being particularly illustrated in Fig. 3.

In the form of control diagrammatically illustrated in Fig. l, the feathering and unfeathering operations of the propeller are instigated by a manually controllable lever I8. This lever simultaneously controls a fluid valve, generally indicated at 80, and an electric switch, generally indicated at 82, and is movable in one direction to swing the propeller to its feathered condition 'and in the other direction to return the propeller from its feathered condition to the constant speed control range of governor pitch angles.

Assuming that it is desired'to change the propeller from the. constant speed control range to a feathered condition, the lever 18 is moved upwardly, as shown in Fig. 1, to connect the conduit 84 leading'from the outlet of the pump 42 with the channel 88 leading from the valve 80 through the check valve 88 to the conduit 90 which leads to a cylindrical aperture 82 formed in the governor 40 or some convenient part of the propeller driving engine and. connected with the conduit 48. Within the bore 82 there is a check valve generally indicated at having a slidableplunger 88 urged upwardly by a compression spring 88. The outlet from th governor actuated valve is connected with the valve chamber 82 through a suitable passage I00. The construction and operation of the valve 84 is particularly illustrated anddescribed in United States Patent fluid pressure in the conduit 90 exceeds the pressure in'the channel I00 the valve plunger 88 is forced downwardly to connect the channel 90 that the high pressure fluid used for featherin the propeller will not feed back through the govemor and the booster pump 48. When the pressure in the conduit 80 is relieved the gpring 00 will force the plunger 08 upwardly to again connect the channel I00 with the conduit 48 to thereby restore the propeller to the governor control.

- When' the lever 18 is moved upwardly to connect the feathering pump outlet 84 with the'conduit 00 it simultaneously closes the switch 82 as the ro'lmded protuberance I02 on the lever moves past the rounded head I04 01' the switch stem. When the switch 82 is closed a circuit is utab lished from the battery I08 through the solenoid Energization of the solenoid I08 closes the relay switch I20 against the force of the spring I22 and energizes the feathering pump motor I24 so .that the feathering pump 42 is put into operation. Energization of the solenoid H maintains the switch 82 closed against the force of the spring I26.

With the pump motor I24 energized the pump 42 withdraws hydraulic fluid from the reservoir or tank I28 through th pump inlet I30 and forces the fluid through the channels 84, 86 and the valve 88 into the conduit 90 wherein the fluid acts to force the valve plunger 96 downwardly and flow into the conduit 48 leading to the collector ring 50 andthe pitch changing motor 24 through the interior of the drive shaft I2 and the distributor valve 54. The fluid flows from the distributor valve 54 .through the channel 60 to th pitch increasing side of the piston 30 and moves this piston to its limiting position in the outer end of the cylinder 32 incidentally rotating the blades I6 to their feathered position. As soon as the blades have reached their feathered position and the piston has reached its limiting position so that further flow of fluid to the pitch changing motor is stopped a rapid increase in the pressure of the fluid in the line between the pump 42 and the pitch changing motor takes place. The pressure responsive switch H2 is connected with the channel 86 through a suitable conduit I82 so that this pressure increase is applied to the switch II2 to open the switch. As soon as the pressure responsive switch is open the electric circuit above described is broken and the solenoids I08 and I III are de-energized. De-ener'gization of the solenoid I08 permits the spring I22 to open the switch I20 and discontinue operation of the motor I24 while de-energization'of the solenoid I I0 permits the spring I26 to open the switch 82. As soon as the pump 42 ceases operation the pressure in the line between this pump and the pitch changing motor falls oil permitting the pressure responsive switch II2 to close but, as the switch 82 is now open, operation of the pump 42 will not be resumed and the propeller may be permitted to nects with the conduit 90 around the check valve 88 which prevents the. application of the un-. feathering fluid pressure to the switch I I2. This downward movement of the lever I8 closes the switch 82 and starts operation of the pump 42 'by energizing the motor I24 in the manner described above. The pump 42 will continue operation building up a 'ufllcient pressure to move the propeller blades out of their feathered position. As soon asthe blades come out of their feathered position the propeller will begin to windmill due to the action of air forces thereon and will rotate the propeller driving engine and drive the pump 46. As soon as the pump 46 begins to operate at a reasonable speed it builds up hydraulic pressure in the channel I00 and causes hydraulic fluid to flow through the ports I36 n the hollow valve member 96 and through the conduit I38 to the pressure responsive switch II4. This switch operates at a relatively low pressure, for example two hundred pounds per square inch, to break the electric circuit energizing the solenoid I88 thereby permitting the spring I22 to open the switch I20 and tie-energize the motor I24. When the pump 42 has ceased operation the fluid pressure in the conduit 90 will be relieved and the spring 88 will move the valve member 96 upwardly to connect the channel I00 with the conduit 48 and restorethe propeller to the control of the governor 40. Since the solenoid I I 0 will also have been de-energized and the switch 82 opened by the spring I26 the pump 42 will not resume operation until the lever I8 is again operated to feather the propeller.

In. case the propeller should stick in its feathered position or it should be attempted to unfeather the propeller when the connected engine is not capable of rotation, the relief valve I40 will open to connect the outlet of the pump 42 with the inlet thereof through the channel I42 to prevent the pump building up a fluid pressure which might endanger the control system.

It will be noted that when the unfeathering pressure is applied to the distributor valve 54 the valve plunger 66 will be moved against the force of the spring I44 to the position shown in Fig. 3 in which the channel I0 is connected through the branch I46 and annular groove I48 in the stem 66, with the channel 80 leading to the pitch increasing side of the piston 30, and the channel 62 is connected through the annular groove 64 in the stem 66 with the channel 12 leading to the pitch decreasing side of the piston 80, to apply the hydraulic pressure to the pitch decreasing side of the piston while simultaneouslyconnesting the pitch increasing side with the engine lubricating system so that any fluid trapped on this side of the piston may vent through the pressure relief valve I6.

In the form of invention shown in Fig. 3, a safety valve I50 may be incorporated in the distributing valve 54 in order to relieve the fluid pressure in the outer end of the cylinder 82 before such pressures reach a dangerous value.

In the form of the invention shown in Fig. 4

the wiring system ha been slightly rearranged and the hydraulic valve 80' omitted. In this arrangement the ground H6 is applied to the pressure responsive switch I I4 only and the switch II 2 has an independent ground connection'ln. The manually operable lever I54 hasa neutral position, as illustrated, towhich it is urged by the opposed compression spring I56 and I58 and carries two opposed switch elements I60 and I62 which cooperate with a single relatively fixed switch element I64 disposed between them.

The lever is also operatively associated with two either one of its operative positions.

With the arrangement shown in Fig. 4, when it is desired to feather the propeller the lever or button I54 is pushed inwardly until the element I60 contacts the element I64. An electric circuit will then -be completed from the ground II8 to the battery I06,-the solenoidl08, the

- switch elements I64 and I60, the solenoid I68.v

The pump will then operate to displace the valve element 86 and supplyhlgh pressure fluid to the pitch increasing side ofthe propeller pitch chan ng motor in the manner described above in connection with-Fig. 1. As soon as the protact with the switch element I84.

42 in the manner described above and when the solenoid I88 is tie-energized the spring I58 will return the lever I54 to the neutral position illus trated breaking the contact between the switch elements I80 and I84. The propeller will then be left in its feathered condition and the pressure in the pitch changing motor and the line between this motor and the "pump 42 will be relieved through the pump 42.

When it is desired to return the propeller to the operative or governor controlled range of pitch angles, the lever or button I54 is pulled outwardly to bring the element I82 in contact with the switch element I84. The solenoids I08 and- I88 are then energized and the current flows from the battery I08 through the solenoid I08, the solenoid I88 and the pressure responsive switch H4 to the ground connection H8 thus completing the circuit between the ground connections H8 and H8. The solenoid I08 closes the switch I20 and puts the pump 42 into operation. and the solenoid I88 maintains the switch elements I84 and I82 closed until the propeller has been unfeathered.- As soon as the propeller starts rotating. at suillcient speed to operate the pump 48 and build up pressure from this pump the propeller reaches its feathered position and the travel of the piston ceases the consequent pressure surge in the line between the pump 42 and the propeller pitch changing motor will operate the pressure responsive switch H2 to interrupt. the circuit including the solenoid I18. will permit the spring I12 to move, the lever I10 and open the switch I14 which will in turn de-energize the solenoid I08 thereby permitting the spring I22 to open the switch I20 and deenergize the motor I24. return the propeller from the feathered condition to the operative or governor controlled range of pitch angles the lever I10 isagain pushed in to close the switch I14 to resume operation of the high pressure pump 42. Since itrequires a higher pressure to unfeather the proin the line I38, in the manner described above, v

the pressure responsive switch II4 operates to break the above described circuit and de-energize the solenoids I08 and I88. When the solenoid I08 is de-energized, the switch I20 is opened by the spring I22 to discontinue operation of the feathering pump and when the solenoid I88 is deenergized the spring I 88 returns the lever I54 to the neutral position illustrated, in which the switch elements I80 and I82 are both out of con- The u 42 will then remain inoperative and the control of the propeller pitch will be taken up by the governor 40.

In the arrangement shown in Fig. 5 the hydraulic valve 80 and the pressure .responsive different-method of,operation but one which is entirely satisfactory for certain installations. In this arrangement the manually controlled lever or button I10 is urged outwardly by a spring I12 to open the switch I14 and is retained in switch closing position by a solenoid I18.

If it is desired to feather the propeller with the'control mechanism illustrated in Fig. 5 the button I10 is pushed inwardly until the switch I14 ,is closed. The current will then flow from the battery I08 through the switch I14 and through the solenoid I08 to the solenoid ground connection I18 and will also flow by a parallel switch II4 are both omitted providing a slightly circuit through the solenoid I18 and the pressure responsive switch II2 to the ground connection closed during the feathering operation. Who

peller than to bring the propeller to its feathered condition the pressure responsive-switch II2 would operate to break the circuitof the solenoid I18 before the propeller moves from the feathered condition and it is, therefore, necessary to manually hold the member I10 in position to maintain the switch. I14 closed until the propeller comes out of feather and under the influence of aerodynamic forces. As soon as the propeller has returned to the operative .or-governor controlled range of pitch angles the member I10 will be released to discontinue operation of the pump 42 as otherwise the propeller would be moved to and retained in its limiting low pitch condition.

The pump 42 and motor I24 will ordinarily be constructed as a unitary electric pump device and may be disposed in any convenient location in the aircraft and may also be utilized to furnish hydraulic fluid under pressure'for other purposes such as operating wing flaps and retractable landing gear lmechanisni of the airplane. The governor control 88 and switch control 18, I14 or I10, are disposed in locations easily accessible to the pilot or flight engineer, for example, on the instrument panel of the air-' plane.

While a particular arrangement of a propeller feathering and unfeathering control has beenhereinabove described-and somewhat diagrammatically illustrated in three slightly different forms, it is to be understood that the invention is not limited to the particular arrangements so illustrated and described, but that such changes in the size, shape and arrangement of the various parts may be resorted to as come within the scope of the sub-joined claims. Having now described the invention so that others skilled in the art may clearly understand the same, what it is desired to secure by Lettc Patent is as follows:

1. In a control for a feathering-type con trollable-pitch propeller. a power driven pump for featheringand unfeathering said propeller. manually operable means for controlling the operation of said pump driving means, means operative to discontinue operation of said pump driving means when said propeller has reached its feathered condition, said manually operable means beingoperable to resume operation'of said pum'p driving means after the propeller has reached its feathered condition to return the propeller to. its operative range of pitch angles, and means operative to again discontinue operation of said pump driving means when.

said propeller has been returned from its feathered condition.

This de-energization of the solenoid I18 Ifitisnowdesiredto- 2. In a control for a feathering type controllable-pitch propeller, a fluid pressure pump for feathering and unfeathering said propeller, electric motor means for driving said pump, a manually operable switch for controlling the operation of said pump driving means, a first pressure operated switch for discontinuing operation of said pump driving means when said propeller has reached its feathered condition, and a second pressure operated switch for discontinuing operation of said pump driving means when said propeller is returned from its feathered condition to its operative range of pitch angles.

3. In a control for a feathering type controllable-pitch propeller, a fluid pressure pump for feathering and unfeathering said propeller, an electric motor drivingly connected with said pump, a relay switch for controlling the motor, a spring for opening and a solenoid for closing said switch, a manually operable switch for controlling the solenoid circuit, a spring for opening said manually operable switch and a second solenoid in said solenoid circuit for maintaining said manually operable switch closed, and two fluid pressure responsive switches in said solenoid circuit one of which acts to break said solenoid circuit when the propeller is fully feathered and the other of which acts to break said solenoid circuit when the propeller is unfeathered.

4. In a control for a feathering type controllable-pitch propeller, a fluid presure pump for feathering and unfeathering said propeller, an electric motor drivingly connected with said pump, a relay switch for controlling the motor circuit, a spring for opening and a solenoid for closing said switch, a manually operable switch for controlling the solenoid circuit, a spring for opening said manually operable switch and a second solenoid in said solenoid circuit for maintaining said manually operable switch closed, two fluid pressure responsive switches in said solenoid circuit one of which is operatively connected with the outlet of said pump and acts to break said solenoid circuit when the fluid pressure in said pump outlet exceeds a propeller feathering value and the other-of which acts to break said solenoid circuit when the propeller is unfeathered, and a fluid valve operatively associated with said manually operable switch to disconnect said onepressure responsive switch from said pump outlet when said manually operable switch is actuated to unfeather said propeller.

5. In a control for a feathering type control-- lable-pitch propeller having a fluid pump and a governor for controlling the pitch thereof in the operative range of pitch angles, a feathering and unfeathering pump, a motor therefor, a relay switch for controlling the operation-of said feathering and unfeathering pump motor, a spring for opening and a solenoid for closing said. relay switch, a manually operable switch in the solenoid circuit, a spring for opening said manually operable switch and a solenoid controlled by said manually operable switch for maintaining the same closed, and a pair of fluid pressure responsive switches in said solenoid circuit one of which is operatively connected with the outlet of said 6. The arrangement as set forth in claim 5 including a fluid valve operated in conjunction with said manually operable switch to disconnect said one pressure responsive switch from said pump outlet when said manually operable switch is actuated to unfeather the propeller.

7. In a control for a, feathering type controllable-pitch propeller, a pump for feathering and unfeathering said propeller, a motor therefor, a solenoid operated switch for controlling said pump motor, a manually actuated switch for closing the circuit for said solenoid, a second solenoid 1 v in said circuit for maintaining said manually actuated switch closed, a pressure actuated switch in said circuit for releasing said manually actuated switch when said motor driven pump develops a hydraulic pressure sufficient to feather said propeller to interrupt said circuit-and discontinue operation of said pump motor, said manually actuatable switchbeing manually operable to reclose said circuit and continue operation of the pump motor to unfeather said propeller.

8. In a control for a. feathering type controllable-pitch propeller, a pump for feathering and unfeathering said propeller, a motor therefor, a manually actuatable switch, a spring urging said switch to open position, a solenoid for maintaining said switch closed when said solenoid is energized, a circuit for said solenoid including said manually actuatable switch and a pressure actuated switch in series, said pressure actuated switch being efiective to interrupt said solenoid circuit and open said manually actuatable switch when said pump develops a hydraulic pressure suflicient. to feather said propeller, a relay switch for controlling said motor, a spring urging said relay switch to open position, a second solenoid outside of said governor controlled range, a gov-.

ernor, a source of hydraulic fluid at a first pressure for changing the propeller pitch within said governor controlled range, a motor driven pump for supplying hydrauiic fluid at a second pressure higher than said first pressureto feather said propeller and for supplying hydraulic fluid at a third pressure higher than said second pressure to unfeather said propeller, and a source of power for said pumpdriving motor, a switch between said source of power and said motor, a spring urging said switch toopen position, a solenoid for closing said switch, a circuit for energing said solenoid, a manually actuatable switch in said circuit, a springfo'r urging said manually actuatable switch to open position, a second solenoid in said circuit for maintaining aid manually actuatable switch closed to continue operation of said pump, and a pressure actuated switch in said circuit operative to interrupt said circuit and thereby discontinue operation of said pump when the fluid pressure developed by said pump reaches said second pressure, said manually actuatable switch being effective when reclosed to resume operation of said pump to develop said third pressure.

10. In combination with a controllable-pitch propeller having movably mounted blades and pitch changing means operative to move said blades to a feathered position, a pump for supplying hydraulic fluid under pressure to said pitch changing means for feathering and unfeathering said propeller, a motor for driving said pump, a fluid pressure operated reversing valve automatically operative to apply the pressure fluid from said pump to said pitch changing means in a manner to unfeather said propeller upon continuation of 'pump operation after the propeller has been brought to a feathered condition, manlable-pitch propeller, a fluid pressure pump'for feathering and unfeathering said propeller, an electric motor drivingly connected with said pump, a relay switch for controlling said motor,

a spring for opening and a solenoid for closing said switch, a manually operable switch for controlling the solenoid circuit, a spring for opening said manually operable switch and a second solenoid in said solenoid circuit for maintaining said manually operable switch closed, and a fluid pressure responsive switch in said solenoid circuit automatically actuated by the rise insaid fluid pressure when said propeller reaches its fully feathered position to interrupt said solenoid circuit and discontinue operation of said pump, said manually operable switch-being operative upon manual closing thereof with the propeller in feathered condition to resume operation of said pump to unfeather said propeller.

I MURRAY 0. 'BEEBE, Jn. 

